Water heater



C. M. OSTERHELD Dec. 12, 1950- WATER HEATER Filed Jan. 4, 1947 INVENTOR. CLARK M. OSTERHELD BY I 4 TT'Y Ill/llll/II Patented Dec. 12, 1950 WATER HEATER Clark M. Osterheld, 'Stoughton, Wis., assignor to Mc'GrawElectric Company, .EIgin, 111., -.a corporation: of' Delaware Amp ification-January 4, 1947;8erial-No; 720,164

e Claims.

My invention relates to electric heaters :and

particularly .to electric .water heaters.

obiectof my invention'is to provide a novel form of internal electric water heater.

Another object of my inventionis toprovide. an

internal electric Water heater that shall comprise a;novel form of electric insulation.

IOther objects ofn y invention will either be apparent froma description of several forms of water heater embodying my invention or will "be pointed out in the course of such. description and set forth particularly in the appended claims.

In the drawings; Figure lis a view in vertical section oiya stand: ard domestic hot water .tank having associated therewithlan electric water. heater embodyin my withapart thereof in sectionaof a modifiediorm,

Fig.6 is an end view of theidevice of Fig.v 5,,

Fig. 31 is. a fragmentary view of a still further modification, and,

Fig. 8 is an end view of the device of Fig.2.

.Referringzfirst of all to Fig.1 of, the drawings, I have there shown a standard. domestic hot water tank H having'a lower closure member 13 which 'isprovided with a cold water inletpipe :15. lprovidealso an .upper closure I51. whichis ,provided with a hot water outlet pipe 19. I provide also a mass of heat insulation 2! such as mineral wool, which heat insulation is held in proper operative position around tank H by an outer casing 23.

An electric heater 25 embodying my invention i comprises an outer tubular metallic member 21 having a closed inner end, which may be made of any suitable metal but is preferably made of relatively thin aluminum, the thickness of this aluminum, being on the order of .035. have given a preferred thickness I do not desire to be limited to this thickness but may make the thickness from .03" to .04". The tube 21 is preferably bent to zigzag form so as to comprise a plurality of substantially straight 'convolutions.

I provide a resistor 29 which resistor is wound to helical form of such dimensions that the outer portions of each turn shall engage the inner surface of tube 21. While I may use standard electric resistance wire I prefer to make the material While I oftresistorlfl .of aluminum and while I :have shown the resistor-conductor as beingsubstantially circular .Imay use any other shape of conductoriin elateralsecti'on.

.Izcover the entire .outer'surface of resistorconductor 29 with .an integral, inorganic, heat-conducting,'high-temperature-resisting and electricinsulating coating, the thickness of this. coating :beingon the'order of .001" although the'thicknesssmay var-.yfrom :0005" to .0015".

While I have hereinbefore stated-that only the conductor is .covered withan electric-insulating coating 1 may also provide :a :similar coating .on the aluminum tubular member 2.1 on :both the inside and the outsidesurfaces.

In forming the electric heater I insert the electrically wound .conductor .29 in tube 21 and then bend the tube to substantially ,zigzag form. it :being evident that there will the no :short circuit occurring between adjacent *turns at the point where ;they come close-together asrshownrat 3l in Fig. 2.. of. the drawings.

I mount the outer end of tube 21 on aaplate 13.3, which .plate isadapted to be mounted against a plateis35 :whichpmay be :securedragainst "the outer convexsurfacev of tank ii I' as by'a .weldedseam 31. Isupport'the .h-eaterl 5 on plate 33 as by aiweld'ed seam 39,- it :being understood that the shape .of plates 33 and 31 are :made'rsuclr :as "to cooperate with each other to provide a watertight joint when secured "against the outer surface of tank I l over-an/opening 41 provided therein. The inner endof "tube 21 is closed and the inner end of resistance-conductor 21 isbrought. out atthe. front end thereof by a conductor 43 which conductor may be a part of conductor 29. An externallythreaded nut 45 is adapted to be screwed into plate 33 to hold the heater 25 in fixed and proper operative position within the tank. It is evident that the diameter or size of opening 4| must be such that bent tube 21 may be inserted into opening 4| and into tank H.

I may hold heater 25 in proper operative watertight position against plate 35 as by a plurality of bolts 41, each having a nut 49 screwed thereon, bolts 41 being secured to plate 35.

Referring now to Figs. 5 and 6 of the drawings, I have there shown a modification of electric heater comprising a preferably aluminum tube 51 having a closed inner end and a thickness as hereinabove set forth in connection with tube 21 and having therein a resistance conductor 29. The only difference between the design shown in Figs. 5 and 6 and that shown in Figs. 1 to 4 inclusive is that tube 5! is wound to extended helical shape.

It is evident that tube 51 may be easily and quickly inserted in tank I 1 through opening 4| by merely screwing in the helically wound tube 5| until the straight end portion 53 is positioned in opening 4| when it may be held in watertight engagement by means similar to that shown as applied to electric heater 25 in Figs. 1 and 2.

Referring now to Figs. '7 and 8, I have there shown another modification comprising a tube 55 which is bent to acute angles in zigzag form. Although I have shown these angles connecting the zigzag portions as sharp it will be understood that it will probably be impossible to make them as sharp as shown in Fig. 7 of the drawings. stantially the same comments as hereinbefore made in connection with the heater construction shown in Figs. 1 and 2 apply also to the heaters shown in Figs. 5 and 6 as well as to those shown in Figs. '7 and 8.

Internal heaters of the kind heretofore used have been of substantially hairpin shape, comprising a tube enclosing a resistance conductor, which is bent to hairpin shape and while the plane of the hairpin will be substantially horizontal the amount of heat-transmitting surface provided thereby will not be anywhere nearly equal to the heattransmitting surface of any one of the designs shown in Figs. 1, 5 and '7 of the drawings. Considerable trouble has been experienced with water containing lime, which lime is deposited upon the relatively high-temperature surface of the electric heater and since my electric heater provides a much greater heat transmitting area the amount of lime, if any, deposited upon the external surface of the heater tube will be much less.

This lesser amount of heat energy transferred per unit area of electric heater results in substantially perfect freedom of lime deposits, thereby providing an electric heater which will operate for extended periods of time before it becomes necessary to remove the heater and clean its external surface.

Various modifications may be made in the de vice embodying my invention without departing from the spirit and scope thereof and I desire that all such modifications coming clearly within the scope of the appended claims shall be considered a part of my invention.

I claim as my invention:

1. In'combination in an immersion type electric l'ieater for a water tank or the like, a sealing member adapted to be mounted on a tank for sealing an opening therein and for supporting a heat- Sub- . er in the tank, an elongated tubular casing having one end supported on and sealed to said sealing member and having the other end closed, said casing having lateral dimensions small enough to pass through a tank opening that said sealing member is adapted to close, said casing being convoluted in a screw shaped pattern that is wider than said opening whereby said convolute casing is much longer than the longer dimension of the space it occupieaand may be mounted in said tank by being threaded through said opening,

and an electric resistor element in said casing extending substantially from said sealing member to said closed end.

2. In combination in an immersion type electric heater for a water tank or the like, a sealing member adapted to be mounted on the tank for sealing an opening therein and for supporting a heater in the tank through said opening, an elongated heating unit having one end fixed to I said sealing member and supported thereon, said I heating unit having lateral dimensions small enough to permit it to pass through the tank opening, and being convolute in a screw shaped pattern that is wider than said opening, whereby said convolute heater occupies a space, the longest dimension of which is much shorter than the developed length of the heater, and may be assembled to said tank by being threaded screwlike through said opening.

3. The combination of claim 1 wherein said tubular casing is substantially round in cross section, said electric resistor element comprises a wire formed in a helix that fits snug in said casing,

andwherein said wire has on its entire surface, an integral, inorganic, heat-conducting, hightemperature-resisting, electric-insulating coating.

- CLARK M. OSTERHELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

